This invention relates to a sealed electrolytic capacitor package and more particularly to an elastomeric grommet and through-lead assembly for effecting the package seal, and more particularly to such a package having tapered lead holes in the grommet.
An elastomeric grommet-through-lead assembly that is presently used extensively for the sealed packages of low cost electrolytic capacitors comprises a rubber stopper or bung adapted at an outer periphery to be sealed in an open end of a metal housing. The bung usually has two cylindrical holes each having an unstressed diameter slightly less than the diameter of the riser portion of a lead that is subsequently pressed into a grommet hole to effect a compression seal therebetween. The riser portion extends completely through the grommet and a smaller diameter lead wire usually of copper or copper clad steel is welded to each riser portion to provide a solderable lead for connecting the packaged capacitor into an electrical circuit system. Thus the grommet is in uniform compressed contact with this riser lead portion for the entire length of the grommet hole.
It is also known to employ a stepped hole in the grommet whereby a cylindrical portion of the hole near the outer face of the grommet is compressed about the wire portion of the lead and a larger cylindrical portion of the hole near the inner face of the grommet is compressed about the larger riser portion of the lead.
However, these commonly employed lead seal constructions have the serious disadvantage that the lead is too easily pulled out of the grommet. Consequently when an electrolytic capacitor package of conventional construction is mounted by the leads to a printed circuit board, for example, and the capacitor package is mechanically pushed or shocked laterally as by inadvertently striking either the board or the capacitor package housing, one or both leads is typically pulled out of the originally mounted position in the grommet. This typically causes a weakening or complete disruption of the lead to grommet seal and in some cases damages the lead to capacitor section connection, in either case causing serious damage to the capacitor.
It is a primary object of this invention to overcome the above noted disadvantages.
It is a further object of this invention to provide a low cost electrolytic capacitor package with sealed leads that are characterized by having a high lead-pull strength.
It is a further object of this invention to provide a highly effective seal between a lead and an elastomeric grommet.